1. Field of the Invention
The present invention relates to norbornene monomers containing an organometal and its manufacturing method, especially to norbornene monomers with a novel functional group containing an organometal used for the manufacturing of a photoresist, and its manufacturing method.
Furthermore, the present invention relates to photoresist and its manufacturing method, especially to phtoresist which can form high resolution patterns in deep-UV wavelength region by copolymerizing aforementioned norbornene monomers or by copolymerizing norbornene monomers with other material, and its manufacturing method.
Still furthermore, the present invention relates to a method forming the aforementioned phtoresist patterns.
2. Description of the Prior Art
With increasing integration of semiconductor devices, there may be a heightened need to form finer patterns of subquarter micron in photolithographic processes. According to the request of fine patterns, processes that can form patterns utilizing deep-UV light from KrF eximer laser with wavelength of 248 nm or ArF eximer laser with wavelength of 193 nm which have shorter wavelength than existing g-line with wavelength of 436 nm or I-line with wavelength of 365 nm came to be necessary.
The photoresist containing Novolac-naphtoquinonediazide compounds utilized in the g-line and I-line has strong absorption in the deep-UV region and is low in sensitivity that it can not be applied in the deep-UV wavelength region. Therefore, the development of new photoresist is required.
New photoresist should satisfy various requirements such as high sensitivity, contrast, high resolution, and resistance to dry etching process. Among them, the sensitivity is the most important in the development of photoresist and the concept of chemical amplification is introduced to enhance sensitivity.
The chemically amplified photoresist is comprised of photosensitive acid generator (PAG) and a polymer combined with dissolution inhibitor.
The exposure of the chemically amplified photoresist hydrolyzes dissolution inhibitor on a polymer main chain by the catalytic reaction of acid from photosensitive acid generator, and the polarity of polymer is changed. Its development in polar or nonpolar solvent yields positive or negative type photoresist patterns. U.S. Pat. No. 4,991,628 discloses the use of polyvinylphenol protected by t-butoxycarbonyl functional group for the application in the chemically amplified photoresist.
However, both the conventional positive or negative type chemically amplified photoresists have several problems. Major problems are deformation and collapse of resist pattern in a wet developing and rinsing according to the increase of aspect ratio of a pattern.
To overcome the problems, the strength of matrix polymer contained in photoresist and the adhesion of photoresist to substrate must be good and appropriate developing and rinsing solution should be selected. However, the solution has also limits because the increase of aspect ratio is inevitable and adhesion has limit, too.
Therefore, the first object of the present invention is to provide norbornene monomers containing novel organometal for the manufacuture of photoresist, which can form high resolution patterns in deep-UV wavelength region.
The second object of the present invention is to provide a norbornene monomer manufacturing method containing appropriate organometal to achieve the above described object.
The third object of the present invention is to provide photoresist utilizing norbornene monomers supplied by achieving the first object.
The fourth object of the present invention is to provide a photoresist manufacturing method suitable to achieve the third object.
The fifth object of the present invention is to provide a method for forming patterns of photoresist, which is supplied by achieving the third object.
Norbornene monomer containing organometal for photoresist according to one embodiment of the present invention to achieve the above first object is presented in the following Formula (I), 
wherein R1 to R8 independently represent hydrogen, alkyls having from 1 to 4 carbon atoms, alkoxy having from 1 to 4 carbon atoms, phenyl or xe2x80x94MRxe2x80x23; M is either Si, Ge, Sn or OSi; and Rxe2x80x2 is either alkyl having from 1 to 4 carbon atoms, alkoxy having from 1 to 4 carbon atoms, phenyl, benzyl or phenoxy.
Norbornene monomer containing organometal for photoresist according to another embodiment of the present invention to achieve the above first object is presented in the following Formula (II), 
wherein R1 to R10 independently represent hydrogen, alkyls having from 1 to 4 carbon atoms, alkoxy having from 1 to 4 carbon atoms, phenyl xe2x80x94MRxe2x80x23; M is either Si, Ge, Sn or OSi; and Rxe2x80x2 is either alkyl having from 1 to 4 carbon atoms, alkoxy having from 1 to 4 carbon atoms, phenyl, benzyl or phenoxy.
The norbornene monomer manufacturing method according to one embodiment of the present invention to achieve the above second object is characterized as follows; Alcohol containing organometal as shown in the Formula (XII) or (XIII) is synthesized. The alcohol is reacted with 2-chlorocarbonyl-5-norbornene derivative at 0xc2x0 C. at ambient atmosphere for 1xcx9c2 hours, and then further reacted at room temperature and ambient atmosphere for 5xcx9c6 hours to yield norbornene monomer as shown in Formula (I) or (II). The synthetic methods for alcohol with Formula (XII) or (XIII) are reported previously (J. Organomet. Chem. 49(1973) C9-C12, J. Org. Chem 45(1980) 3571-3578, Tetrahedron Lett. (1976) 1591-1594, J. Organomet. Chem. (1981) 33-47), 
wherein R1 to R10 independently represent hydrogen, alkyls having from 1 to 4 carbon atoms, alkoxy having from 1 to 4 carbon atoms, phenyl or xe2x80x94MRxe2x80x23; M is either Si, Ge, Sn or OSi; and Rxe2x80x2 is either alkyl having from 1 to 4 carbon atoms, alkoxy having from 1 to 4 carbon atoms, phenyl, benzyl or phenoxy.
The photoresist according to one embodiment of the present invention to achieve the above third object is characterized to comprise a polymer and a photosensitive acid generator as shown in the following Formula (III), 
wherein R1 to R8 independently represent hydrogen, alkyls having from 1 to 4 carbon atoms, alkoxy having from 1 to 4 carbon atoms, phenyl or xe2x80x94MRxe2x80x23; M is either Si, Ge, Sn or OSi; and Rxe2x80x2 is either alkyl having from 1 to 4 carbon atoms, alkoxy having from 1 to 4 carbon atoms, phenyl, benzyl or phenoxy; n is degree of polymerization and is between 1 to 100.
The photoresist according to another embodiment of the present invention to achieve the above third object is characterized to comprise a polymer and a photosensitive acid generator (not shown) as shown in the following Formula (IV), 
wherein R1 to R10 independently represent hydrogen, alkyls having from 1 to 4 carbon atoms, alkoxy having from 1 to 4 carbon atoms, phenyl or xe2x80x94MRxe2x80x23; M is either Si, Ge, Sn or OSi; and Rxe2x80x2 is either alkyl having from 1 to 4 carbon atoms, alkoxy having from 1 to 4 carbon atoms, phenyl, benzyl or phenoxy; n is degree of polymerization and is between 1 to 100.
The photoresist according to another embodiment of the present invention to achieve the above third object is characterized to comprise a polymer and a photosensitive acid generator as shown in the following Formula (V), 
wherein, A represents the following Formula (VII) or (VIII), and 
wherein R1 to R10 independently represent hydrogen, alkyls having from 1 to 4 carbon atoms, alkoxy having from 1 to 4 carbon atoms, phenyl or xe2x80x94MRxe2x80x23; M is either Si, Ge, Sn or OSi; and Rxe2x80x2 is either alkyl having from 1 to 4 carbon atoms, alkoxy having from 1 to 4 carbon atoms, phenyl, benzyl or phenoxy; x,y,z are mole ratio of a polymer and x+y+z=1.
The photoresist according to another embodiment of the present invention to achieve the above third object is characterized to comprise a polymer and a photosensitive acid generator as shown in the following Formula (VI), 
wherein A represents the above Formula (VII) or (VIII), and B represents the following Formula (IX), (X))or (XI), and 
wherein R1 to R10 independently represent hydrogen, alkyls having from 1 to 4 carbon atoms, alkoxy having from 1 to 4 carbon atoms, phenyl or xe2x80x94MRxe2x80x23; M is either Si, Ge, Sn or OSi; and Rxe2x80x2 is either alkyl having from 1 to 4 carbon atoms, alkoxy having from 1 to 4 carbon atoms, phenyl, benzyl or phenoxy. R11 to R13 independently represent hydrogen or alkyl; x,y,z are mole ratio of a polymer and x+y+z=1.
The photoresist manufacturing method according to one embodiment of the present invention to achieve the above fourth object is characterized to comprise the steps of; manufacturing of norbornene monomers as shown in the above Formula (I) or (II); manufacturing of polymer either polymerizing the norbornenes, copolymerizaing norbornenes with maleic anhydride, or polymerizing in a radical method by mixing silicon-containing acrylate or methacrylate monomer as well as maleic anhydride with norbornene monomers; dissolving the above polymer and photosensitive acid generator in solvent.
Benzoyl peroxide, 2,2xe2x80x2-azobisisobutyronitrile, acetylperoxide, laurylperoxide, or di-t-butylperoxide are used for radical initiators for the polymeriazation. Benzene, toluene, tetrahydrofuran or mixtures of them are used for polymerization solvent. The polymerization is performed at 50xcx9c70xc2x0 C. for 6xcx9c30 hours in a flask under nitrogen atmosphere.
Monomers in the above Formula (I) or (II) are polymerized to give a resin for photoresist. However, copolymerization with monomers such as maleic anhydride is desirable to provide better properties such as improved adhesive properties onto substrate or increased glass transition temperature.
On the other hand, as described below one of the characteristics of the present invention is that upon exposure the silicon content of photoresist film is different between the exposed area and unexposed area, which differentiate the etching speed toward oxygen plasma between the exposed area and unexposed area and makes dry developing possible. Therefore, to increase the difference in etching speed, copolymerization of monomers in Formula (I) or (II) with maleic anhydride, silicon-containing acrylate or methacrylate monomers is desirable as explained.
If the aforementioned xe2x80x98Mxe2x80x99 is silicon, it is generally desirable to have more than 7% of silicon to have different etching speed between exposed area and unexposed area. The introduced monomer ratio for a difference in etching speed should be controlled in consideration of silicon weight content, glass transition temperature and adhesion.
The photoresist pattern forming method according to one embodiment of the present invention to achieve the above fifth object is characterized to comprise the steps of; forming photoresist film on a substrate by coating photoresist which is provided through the achievement of the above fourth object; exposing the above photoresist film through exposure mask; baking the above exposed product; selective etching of exposed area in the above photoresist film by a reactive ion etching utilizing oxygen plasma.
Irradiation of deep-UV light on the photoresist film coated on the above substrate produces materials described in the Formula (XIV) or (XV). 
Therefore, in order to remove materials described in the above Formula (XIV) or (XV), baking is followed by the exposure step. The desirable baking condition is at 90xcx9c140xc2x0 C. for 90xcx9c120 seconds. The materials described in the Formula (XIV) or (XV) may have volatility at post exposure baking (PEB) temperature by a suitable modification of R3 to R10 groups, and they can also be removed by extraction if not volatile.
The above photoresist film formation includes steps of; dissolving the polymer with 1-10 wt % of photosensitive acid generator such as triphenylsulfonium triflate or other onium salts in propylene glycol monomethyletheracetate or cyclohexanone solvents followed by filtering to manufacture photoresist solution; spin-coating the above solution on a silicon wafer; soft-baking for 90xcx9c120 seconds on a hot plate at 90xcx9c120xc2x0 C.
In the area irradiated by deep-UV light, the side chain including silicon(designated by M) containing portion is decomposed by an acid catalysts during post exposure baking (PEB) to yield the above Formula (XIV) or (XV) and is then removed. The area which is not irradiated by deep-UV light is stable at post exposure baking (PEB) temperature and the silicon content is not different from the initial content. Therefore, the post exposure baking (PEB) leaves clear latent image on the surface of photoresist. Upon the etching of latent image by oxygen reactive ion etching, the exposure area is removed by decomposition and the unexposed area is not etched due to the SiOx film on the surface resulting from remained silicon components. It results in photoresist patterns.